List of top Petroleum Engineering Questions on Well Testing asked in GATE PE

Three wells are located at the corners of an equilateral triangle inside an infinite acting reservoir. The reservoir is horizontal, homogeneous, isotropic, and of uniform thickness. The initial reservoir pressure is 3000 psi. If only one well had been producing under transient flow conditions, the pressure at the centre of the equilateral triangle would have dropped by 100 psi after 60 days. If all three wells start producing simultaneously under transient flow conditions at the same rate, then after 60 days, the pressure (in psi) at the centre of the triangle is ____________.
Matthews-Brons-Hazebroek (MBH) plots are used to calculate the Dietz shape factor (C_A) for reservoirs of various shapes. The MBH plot for a right-angled triangle reservoir with the well located at the centre shows a reading of dimensionless pressure P_D(MBH) = 3.0, at a modified dimensionless time t_DA = 1.0.
The Dietz shape factor of this right-angled triangle reservoir is ____________ (rounded off to one decimal place).
A drawdown test is analyzed to find the permeability and skin factor of a reservoir using a semi-log plot, where the flowing bottomhole pressure (in psi) is plotted on a linear scale against time (in hours). The flow rate is 1500 STB/day, the oil formation volume factor is 1.2 RB/STB, and the oil viscosity is 1 cP. The thickness of the producing bed is 10 ft. The slope of the straight line fitting the data in the middle time region of the semi-log plot is 60 psi/log cycle.
The permeability of the reservoir (in mD) is _______ (rounded off to one decimal place).
Pressure change and derivative type curves (Bourdet type curves) are used in well test analysis. Which of the following statements is/are CORRECT about these type curves?
Which of the following statements is/are CORRECT about the skin factor?
A circular reservoir with a well in the centre is producing oil at a constant rate under pseudo steady state. The rate of pressure change measured at the wellbore is 1.0 psi/day. Pressure at the external radius of the reservoir at a certain time was 3500 psi. After 500 days, the pressure (in psi) at the external radius will be __________.
In a drawdown test conducted on a well, \(p_D\), \(t_D\) and \(C_D\) denote the dimensionless pressure, the dimensionless time and the dimensionless wellbore storage coefficient, respectively. In the early time of the drawdown test, the fluid produced at the surface results purely from the unloading (expansion) of fluid already stored in the wellbore, and no fluid from the formation has reached the well yet. This period is called the pure wellbore storage period. For this period, which of the following relationships is CORRECT?
A circular shaped reservoir has an external radius \(r_e\). A well of radius \(r_w\) lies at the centre of the reservoir. The part of the reservoir around the wellbore, up to a radius \(r_s\), is damaged due to drilling and completion operations, where \(r_w < r_s < r_e\). This formation damage causes an additional pressure drop, \(\Delta p(r)\), that varies with the radial distance \(r\) from the well. Which of the following statements is TRUE about the additional pressure drop at the radial location \(r_s\) due to the formation damage?